Process for chlorinating chlorpropane



atented Dec. 27, 1949 UNITED STAT PROCESS FOR CHLORINATING CHLORPROPANEHooker Electrochemical Company,

Niagara Falls, N. Y., a corporation of New York No Drawing. ApplicationDecember 8, 1944, Serial No. 567,314

3 Claims. (01. 204-163) Our invention relates more particularly tolromotion of organic halogen substitution reacions, especially when itis desired to carry the eaction further than it will readily go undervrdinary-conditions. An example of such a relction is afiorded byphotochemical chlorination If paramnic hydrocarbons to completereplacement of the hydrogen by chlorine. It is known hat such reactionsare retarded or inhibited in )resence of oxygen or the resultingoxygenation )roducts. One of the objects of the invention is promote thespeed and completeness of the 'eaction and carry it further than wouldothervise be practicable under such conditions.

The partial chlorination of hydrocarbons of all :inds is comparativelyeasy. The complete chlo- -ination of hydrocarbons is much moredifficult. Methane and ethane are about the only hydro- :arbons thathave hitherto been fully chlorinated in a commercial scale.

We will describe our process with particular reference to production ofoctachlorpropane. This may be produced without great difiiculty byihlorination of hexachlorpropylene. However, cexachlorpropylene is avaluable product in itself and it is one of the objects of the presentinvention to product octachlorpropane directly from propane.

Propane is derived from natural gas and may be chlorinated, starting invapor phase, to produce mixtures up to the heptachlor, which are liquidat ordinary temperatures. These mixtures may then be further chlorinatedto octachlorpropane in liquid phase. This has been done, on a smallscale, by various processes, all of which are unsatisfactory as to costor yield or both. One of the objects of the present invention is toproduce octachlorpropane by a practicable process, suitable foroperation on a commercial scale, so as to render the produce availableto the arts.

One way in which octachlorpropane has hitherto been produced on a smallscale is by first chlorinating to the heptachlor and thendehydrochlorinating by means of caustic soda to hexachlorpropylenewhich, being unsaturated, may be chlorinated without great diiiiculty tooctachlor Mixtures of chlorpropanes have been further chlorinated inliquid phase to a mixed product containing a minor proportion ofoctachlorpropane by the use of a liquid chlorinating agent,

such as iodine trichloride, antimony pentachlo- "ride, etc., or by theuse of liquid chlorine under high pressures, in both cases at about 200C. At

this temperature there is much-splitting of the molecule to carbontetrachloride and hexachlorethane. These mixtures have also beenchlorin-- ated with gaseous chlorine at atmospheric pressure by the aidof very powerful actinic light, likewise at about 200 C. As before,there is much splitting of the molecule; alsothe intensity of the 1required light limits the size of the chlorinationunits, and the timecycle is excessive.

We have now succeeded in chlorinating mix tures-of chlorpropanes, havinga specific gravity of 1.70 to 1.76, corresponding to a mixture ofpentachlorto heptachlorpropane, by means of gaseous chlorine, and withthe aid of actinic light of moderate intensity (1,200 watts for a 500gallon reactor) at a moderate temperature and pressure to 150 C. andlOto lbs. per sq. in.

(respectively), with an almost quantitative yield of octachlorpropane.

prior to further chlorination thereof, with a basic substance, such asthe alkali metal'and alkaline earth hydroxides and alkali metalcarbonates, in such small quantities and under such conditions as tocause no appreciable dehydrochlorination of the material or othermodification of its molecular structure. This treatment is effected byagitating the liquid chlorpropane mixture with a small quantity of thealkali, amounting to one or two per cent by weight, at 35 to 90 0., forfrom 30 to 60 minutes, and then filtering out the solids from the liquidmaterial," and thus removing any solid or colloidal suspendedcontaminants. Without this treatment the further chlorination of thechlorpropane mixture, under the conditions as to temperature andpressure indicated above, is'impracticable, if not impossible.

After this treatment, however, the chlorination: proceeds rapidly andsmoothly to substantial completion, with an almost" quantitative yield,

as above stated.

The product obtained by our process as above crystalline product,

described analyzes within one per cent or less of the chlorine contentcorresponding to octachlor propane made by the process of the prior art.This is within the limits of error of the best known methods fordetermination of chlorine in organic compounds.

Octachlorpropane, such as may be produced by chlorination ofhexachlorpropylene, is a white crystalline material melting at 150 C.and theoretically containing 88.7 per cent chlorine. It may be readilyground to a powder. Our product contains 88+ per cent chlorine byanalysis and melts at 120 to 155 C. It has a tough waxy consistency andcannot be ground. It gives off only 0.02 to 0.04 per cent of itschlorine when maintained at 140 C. for 16 hours. This is an evidence ofa high degree of stability as compared with chlorinated hydrocarbons ingeneral,

some of which would give off 30 per cent of their chlorine under similarconditions.

Why our octachlorpropane product should have physical characteristicsdifferent from those of the prior art product, is not at present known.At any rate, the diiferent physical properties of our product, ascompared with those of the give it greatly enhanced value. For example,it is firmly adherent to smooth surfaces. It is compatible withlubricating oils and is itself an excellent lubricant for such surfacesas those of plug cocks and bearingj's exposed to highly corrosivechemicals, such as chlorine, HCI, H2804, etc. It is also an excellentplastici zer for natural and synthetic resins, formingtherewith a greatvariety of compositions suitable for impregnation and coating, for thepurpose of fireproofing and weather prooiing. 7

Our octachlorpiopane product also forms with other chlorinatedhydrocarbons a whole series of compositions having useful properties..In particular it forms with hexachloretha'ne a series of compositionswhich are unique in that, although fully chlorinated, they arenevertheless of a tough waxy consistency, being in this respect entirelyunlike compositions produced by blending hexa'chlorethanei with purecrystalline octachlorpropane.

Example I 1150 lbs. of'chloipropane mixture having a spe cific gravityof 1.73 corresponding to a mixture consistingm'ostly of pentachl'or. toheptachlo'rpro pane", were agitated withlbs. of oa(oH)2 at 90 for onehour and the material passed through a filter press. The filteredmaterial Weighed 1110 lbs. This Was chlorinated under actlnic light asfollows:

The product was blown for 15 minutes with CO2 to remove dissolved H01and C12. When cast and cooled into a slab and dropped onto a hardsurface it emitted a metallic clink. It could not be ground. It wassubstantially colorless" andof a waxy consistency, analyzed 88+ per centchlorine. and had a first crystal point of 143 0., a

, first example.

The product of Example I was blended with liexachlorethane in variousproportions ranging from 20 to 200 per cent of its weight of the latter,and" the cloud points determined. It was found that the mixturecontaining 20 per cent of hexachlorethane had a cloud point of about 108GA, which was thelowest cloud point obtained. This composition wastransparent, tough and extremely flexible. When melted and poured on"glass it could not be chipped or scraped off or otherwise removedwithout the aid of heat or a solvent- It proved tobe inert to a ueous HFglass etching soiution. When rolled out a sheet it was found to haveconsiderable tensile strength and elasticity, and when out into stripsthese could be twisted and tied into knots.

, Example III Two identical portions air blown to saturation withoxygen. One was given the alkali treatment, as in Example I'. The otherwas not treated. rinated to octachlorpropane, likewise as in the Thealkali treated portion re quired zc'ncurs' aia'd 1.022'lbs.

lbs. of chlorine per pound of product. The second required '75 hours andconsumed 1.545 lbs. of chlorine per pound of product. This shows thatoxygen in the chlorine has the same inhibiting effect as oxygen in thehydrocarbon.

Since the reaction is exothermic, the temper:

ature of the reaction mixture a given stage of the reaction, under givenconditions as to radiation" of heat, etc, is a function of the rate ofre action. The effect of the alkali treatment upon the rate andcompleteness of absorption of the chlorine, can therefore be likewisedemonstrated by noting the temperature of the reaction inixture as thereaction proceeds.

Example V 500 c. c. of dichlor'ethane (ethylene dichloride) were airblown for 15 minutes to saturate the lid} uid with oxygen. The samplewas then divided into two equal portions. one part was given a treatmentwith a 10' per centsoliition of NaOH 'for' 30 minutes and dried. Eachportion was of chlorpropane, having the ame specific gravity as inExample I, were Both were then" ch10 H chlorine'per pound. of product.The other required 55 hours and 1.511 lbs. chlorine per pound ofproduct. This";

nlaced in a 250 c. c. flask and the two flasks placed n a constanttemperature bath maintained at $0 C. Both portions were chlorinated atatnospheric pressure by gaseous chlorine introluced at the same rate;namely, 280 c. caper ninute under the same conditions as to actinicight, and the change in temperature with lapse )f time noted. 7

The results were as follows:

Temperature Time Minutes Untreated Treated Portion Portion MOI Theresults show that at 7 minutes both portions were at the sametemperature. After 9 minutes the portion that had been given the alkalitreatment had forged ahead. After 15 minutes, the temperature of theuntreated portion was falling. This is normal; but at the same time thetemperature or the treated portion was rising. This is a whollyunpredictable result.

Example VI The experiment of Example V was repeated with a chlorheptanemixture having a specific gravity of 1.527, corresponding to a chlorinecontent of 70.5 per cent. After 23 minutes this showed the samephenomena, namely a falling temperature in the case of the portion thathad not had the alkali treatment and an anomalous rising temperature inthe case of the treated sample.

Example VII holds for long chain as well as for short chain paraffinichydrocarbons; but also that it is not due merely to neutralization ofHCl.

Example VIII The experiment of Example V was repeated with isopropyladipate. The same anomalous and unpredictable result was obtained. Thatis to say, after 9 minutes the untreated portion was at 62 C. and thetreated portion at 65 C. This shows that the alkali treatment promoteschlorination even when there is oxygen in the molecule. In this case,the reaction was found to be chiefly a substitution of chlorine forhydrogen in the isopropyl group.

Example IX The experiment of Example V was repeated with isopropylbenzoate. The results were the same as before. That is to say, after 6minutes the untreatedportion showed a temperature of 59 C. and thetreated'portion-a temperatureof 62 C. ,-proving that the beneficialefiect of the alkali treatment is not limitedto parafflnic compounds. Asin Example VIII, the reaction was I principally a: substitution ofchlorine for hydrogen in the alkyl-group.

While we have illustrated our process by specific example, we do notwish to be limited thereto, as our-process is evidently applicable tohalogenation of organic materials in general, the halogenation of whichis'retarded in presence of oxygen other than oxygen that may be in themolecules of the material itself, and the molecular structure of whichis not modified by the treatment preparatory to halogenation. Neither dowe wish to be limited to photochemical halogenation, as our process isapplicable to analogousheat or infra-red activated or chain.

mechanism halogenation of organic materials within the above definedcategory which are susceptible of halogenation under such conditions.Likewise, we do not wish to be limited to the alkalis specificallymentioned or used in the ex ample, as any basic reacting substance ismore or less effective in our process, when the conditions of thereaction, i. e., as to the reactivity and concentration of the basicreacting substance, temperature at which the treatment is carried out,time of treatment, etc., are such that there is little or nodechlorination, dehydrochlorination or other modification of themolecular structure of the material.

We claim as our invention:

1. The process for chlorination by substitution of chlorpropane, bymeans of gaseous chlorine, when one of the reagents contains freeoxygen, which comprises contacting the liquid organic material with 1 to2 per cent of its weight of a material of the group consisting of thealkali metal and alkaline earth hydroxides and alkali metal carbonates,for at least 30 minutes; removin the alkaline material and any suspendedsolids from the organic material; and passing gaseous chlorine into theorganic material, at

to 150 C. and under a pressure of 10 to pounds per square inch gauge,under actinic light effective in catalyzing the reaction, until thereaction has gone as far as practicable.

2. The process for chlorination by substitution of chlorpropane mixtureshaving a specific gravity of 1.70 to 1.76, by means of gaseous chlorine,when one of the reagents contains free oxygen, to produceoctachlorpropane, which comprises contacting the liquid organic materialwith 1 to 2 per cent or its weight of a material of the group consistingof the alkali metal and alkaline earth hydroxides and alkali metalcarbonates, for at least 30 minutes; removing the alkaline material andany suspended solids from the organic material; and passing gaseouschlorine into the organic material, at 90 to C. and under pressure of 10to 100 pounds per square inch gauge, under actinic light effective incatalyzing the reaction until the reaction has gone as far aspracticable.

3. The process for chlorination by substitution of chlorpropane mixtureshaving a specific gravity of 1.70 to 1.76, by means of gaseous chlorine,when one of the reagents contains free oxygen, to produceoctachlorpropane, which comprises contacting the liquid organic materialwith 1 to 2 per cent of its weight of calcium hydroxide at 35 to 90 C.for 30 to 60 minutes;

emo izm: tho alkaline; mammal and amr'sius ponded sclid o item. the: oani v maierial: a d pmina asaous: chlorine into the organic: mate-4..rialiat 8,0? to: 150? Radar a, pressure-coi 2a to noundainer square.inch-gauge, under actinic: l ht etfe tive, in. catalyzin the reac ion:until. the reaction has gone aarfar. as; practicable, JAMES S. SQQNG-E;DAVID SzRQSENBER-Q.

N. JQHNSQN:

REFERENCES; CITED he w ng r rence are rco i th file of "patent:

V TATE FAWN-T3 7 Date 8 umber Name Bate 212 11 168 M rsh o-----=.---Aug. 13, 19 0 2,296,614 Hearne Sept. 22, 1942.; 2,318,681 Gaylor May 11,19%: 2,334,033 Riblett, Nov. 9, 19.43

Churchill et a1. Dec. 12, 194.;

' OTHER REFERENCES M Be t a Indus ria and En ine ring 1Q Chemistry,February 1941, pp. 176-181.

Stowart et aL, Journal American Chemical Society, October 1929, pp.30854;.

Mailer, I organic and Theoretical Chemistry. vol. I' (1927), Pp,369-370.

Hackh, Chemical Dictionary, 3d 1.914), p- .1,.-

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